Photoshop CS5 can be run as a 64-bit application on Mac OS, 10.5.7 and higher. Because of the changes that were made to the application, some plug-ins are not available when you run Photoshop CS5 either as a 32-bit or a 64-bit application. To work with these plug-ins, run Photoshop CS5 as a 32-bit application, then when you are done using these plug-ins, return to working in Photoshop CS5 as a 64-bit application.

If you copy old plug-ins from previous versions of Photoshop, or third-party plug-ins that are not compatible with Photoshop CS5, into Photoshop CS5's Plug-in folder, you may see different problems, such as errors or crashes.

If you have set the Additional Plug-Ins Folder in the Plug-Ins preferences to a folder, deselect this option, or make sure all the plug-ins in this folder are compatible with Photoshop CS5.

The easiest way to determine if third-party, old plug-ins, or plug-ins from previous versions of Photoshop are causing problems is to move them all into a new folder called "3rd Party plug-ins."

If this folder is outside the Photoshop/Plug-Ins folder, you can use the Additional Plug-Ins Folder Plug-In preference to allow Photoshop to access or not access the plug-ins in this folder.

If this folder is inside the Photoshop/Plug-Ins folder, disable the plug-ins by renaming the folder by putting a tilde (~) as the first character in the folder name.

Plug-ins not supported by Photoshop CS5 on Mac OS, running in 64-bit mode:

Lighting Effects

Extract (Use Refine Mask under the Selection menu)

Variations

Web Contact Sheet II (Web Photo Gallery)

TWAIN support will work on some scanners

Video Preview

Send Video Preview to Device

Embed / Read Watermark

Firewire

Firewire DLL

To run Photoshop CS5 on Mac OS as a 32-bit application, select the Adobe Photoshop CS5 application file, installed by default in the Applications/Adobe Photoshop CS5 folder. Choose File > Get Info, and select Open in 32 Bit Mode. Deselect this option to run Photoshop CS5 in 64-bit mode.

To determine if a plug-in causes an error or crash, remove all old or third-party plug-ins from the Adobe Photoshop CS5 > Plug-Ins folder, and deselect Additional Plug-ins Folder in the Photoshop > Preferences > Plug-Ins preference.

It shows up, but only AFTER you have a selection active....You have to make your selection first. If it still doesn't show up, you can go to SELECT---REFINE MASK .... and you will get the dialog box.

I'm still having problems, but primarily have been trying with one or two photos. I end up with transparencies and the hair I "painted in" is gray...not brunette...as it should be. I've done Lynda's tutorial and it works perfectly, so I don't really know what's going on. The tech tried with the same photogaph and he said (just tonight...phoned back)...that his turned out worse than mine....sooooo...I'm really in a quandry here.

Let me know if it works for you. I'd be anxious to find out the results you get with the mask....refinement tool.